Three Python repairs pass initial tests but fail on boundary conditions

The Failure Map project presents three Python examples where code fixes appear reasonable but violate contract boundaries. Each example involves standard library functions failing specific edge cases despite passing initial tests. The first case incorrectly uses a set to deduplicate events, losing distinct identities with equal amounts. The second mishandles expiration logic with inclusive comparisons, while the third fails on cursor-based pagination due to incomplete ordering. All cases demonstrate that fixes must preserve full contractual obligations, not just address initial failures.